Comprehensive review on metallurgical recycling and cleaning of copper slag

Abstract

Copper slag, generated mainly during copper smelting, and classified as a potentially harmful waste, is an important secondary resource containing not only valuable metals, such as Cu, Fe, Zn, Co and Ni, in abundant quantities, but also hazardous elements, such as Pb and As. Hence, in response of its potential economic performances and environmental benefits, copper slag needs to be subjected to further metallurgical recycling and cleaning instead of being dumped or abandoned without treatment. Here, a critical review of the generation mechanism, and chemical and physical characteristics of copper slag is provided. Details of the mainstream and recently developed routes for metallurgical recycling and further cleaning of copper slag are also summarised, such as flotation, leaching, and reduction roasting followed by magnetic separation, smelting reduction, and molten modification followed by physical separation. The technical challenges and developmental bottlenecks of the metallurgical processes are pointed out, which indicate that the improved processes characterised by high recycling efficiency, low energy consumption, and low secondary environmental pollution continue to be the focus of research and development in sustainable waste utilization of copper slag.